In some geographical areas there has been a growing concern regarding the use of phosphorus-containing compounds in laundry detergent compositions because of reported links of such compounds to the eutrophication of lakes and streams. While it is not clear whether or not this link is really significant, some governmental bodies have restricted the phosphorus content of detergent compositions, thereby necessitating the formulation of laundry detergents containing chelants which are less effective than the conventionally-used phosphonates or polyphosphonates. These requirements have complicated the formulation of effective and appropriately priced laundry detergent compositions. It would, therefore, be highly desirable to be able to formulate detergent compositions which include reduced levels of phosphorus-containing components and which are at least partially biodegradable, but which still exhibit excellent cleaning and stain removal performance.
In addition, while the use of chelants in detergent compositions is generally thought to be desirable for enhanced stain removal, there is generally believed to be an efficacy/biodegradability trade-off therewith. For example, some chelants which provide superior stain removal (e.g., diethylenetriaminepentaacetates) tend to be nonbiodegradable, while those which exhibit some level of biodegradability (e.g., N-(2-hydroxyethyl)aspartic acid) are relatively poor in terms of stain removal.
It is an object of the present invention to enhance the stain removal performance in detergent compositions, unlimited in type. It is a special object of the present invention to provide laundry detergent compositions containing nil-phosphorus, biodegradable chelants, that possess excellent stain removal characteristics.